How Do ICFs Work?

Concrete Homes
Time: 01:22
Learn about concrete homes built with ICF construction, including the benefits, how they are built, and more.

ICFs are forms for poured concrete walls that stay in place as a permanent part of the wall assembly, serving as continuous insulation as well as a barrier against air and sound entry. To give the wall greater strength, steel reinforcement is placed both horizontally and vertically in the forms before the concrete is pumped or poured inside.

ICF forms are made of various types of foam insulation (see Plastic Foams for Concrete Homes) and come in two basic configurations: hollow-core blocks that stack and interlock like Legos and individual panels or planks that connect with plastic or steel ties. Within these basic categories are many different ICF products, differentiated based on the structural configuration they form (such as a flat wall, post-and-beam, or grid system),how the forms attach together, how finishes attach to the wall, thickness, and insulating values.

Fox Blocks

From a builder's perspective, ICF systems offer numerous advantages over other types of concrete wall construction:

The foam forms are lightweight and easy to erect; bracing and alignment systems are provided by most manufacturers.

Because the forms remain in place, contractors can build concrete walls in less time—in as little as a day for a typical house foundation.

The insulating forms protect the concrete from temperature extremes, permitting concrete to be placed at below-freezing temperatures and extending the construction season by several months in cold climates.

The pre-insulated walls eliminate the need for additional insulation and the labor cost of installing it.

Exterior siding and interior drywall can typically be attached directly to the form faces, with many ICFs incorporating integral attachment systems.